Abstract:
Die Erfindung betrifft Schneckenelemente (10, 10') für mehrwellige Schneckenmaschinen mit paarweise gleichsinnig drehenden Schneckenwellen (W, W'), wobei diese Schneckenelemente paarweise exakt abschabend sind und die aus diesen Schneckenelementen zusammengesetzten Schneckenwellen zwei oder mehr Schneckengängeaufweisen, wobei die Schneckenprofile (11, 11') über den gesamten Querschnitt durch jeweilige Profilkurven darstellbar sind, wobeijede Profilkurve (11, 11') mindestens eine Knick-Stelle (K, K') in ihrem Verlauf aufweist, die innerhalb eines Außenradius (RA, RA') der Profilkurve liegt. Der Knick gilt als eine Stelle der abrupten Steigungsänderung oder der geometrischen Unstetigkeit in der Steigung der Profilkurve. Ferner betrifft die Erfindung ein Verfahren zur Erzeugung von Schneckenelementen (10, 10'), wobei zur Ausbildung der Schneckenprofile (11, 11') Kreisbögen (1-5) zu einer Kurve zusammengesetzt werden, die mindestens eine Knick-Stelle (K, K') bzw. eine Stelle der Unstetigkeit in der Steigung der Kurve in ihrem Verlauf aufweist, wobeidiese Stelle (K, K') innerhalb eines Außenradius (RA, RA') der Profilkurve liegt. Außerdem betrifft die Erfindung Schneckenmaschinen mit den erfindungsgemäßen Schneckenelementen. Weiterhin betrifft die Erfindung die Verwendung erfindungsgemäßer Schneckenelemente für die Extrusion plastischer Massen.
Abstract:
A method and system for melt processing a thermoplastic composition that contains a starch and plasticizer is provided. The composition is melt blended and extruded through a die to form an extrudate, which is thereafter cooled using a multi-stage system of the present invention that includes at least one water-cooling stage and at least one air-cooling stage. More particularly, the extrudate is initially contacted with water for a certain period time so that it becomes partially cooled and solidified on its surface. After the water-cooling stage(s), the extrudate is also subjected to at least one air-cooling stage in which a stream of air is placed into contact with the extrudate.
Abstract:
Apparatus (1) for admixing additives to a medium to be pumped, comprising at least one gear pump (2) for pumping a medium to be pumped, said gear pump (2) comprising at least one shaft (3) having a first driving torque; at least one injector (5) for introducing an additive into a medium to be pumped; at least one screw conveyor (6) for mixing said additive with said medium to be pumped, said screw conveyor having a second driving torque, and, characterized in that, the shaft (3) and the screw conveyor (6) are functionally connected, such that the first driving torque and the second driving torque are coupled.
Abstract:
The present invention provides a method of forming a polymer-wood composite structure and additive systems for use therein. The method of the invention includes extruding a heated mixture that includes from about 20% to about 80% by weight of a thermoplastic polymer, from about 20% to about 80% by weight of a cellulosic filler material, and from about 0.1 % to about 10% by weight of an additive system. The additive system according the invention includes a blend of from about 10% to about 90% by weight of a nonionic compatibilizer having an HLB value of from about 9 to about 19 and from about 10% to about 90% by weight of a lubricant. Use of the method and additive system according to the invention facilitates the production of highly filled polymer-wood composite structures at a very high output rate while maintaining commercially acceptable surface appearance. Moreover, the method and additive system according to the invention facilitate the reprocessing of scrap material generated during the production of polymer-wood composite structures without degrading the surface appearance of the polymer-wood composite structures.
Abstract:
A method of compounding a multimodal, preferably a bimodal polymer composition comprising a low molecular weight ethylene polymer and a high molecular weight ethylene polymer is described. The composition is compounded during a relatively long time at a low temperature which lies in a narrow temperature range including the melting point of the low molecular weight ethylene polymer. More particularly, the polymer composition is compounded, without addition of a heat transfer medium, in a temperature range from about 10 DEG C below to about 10 DEG C above the melting point of the low molecular weight ethylene polymer during a time of more than 10 seconds. The viscosity ratio between the ethylene polymers in said temperature range preferably is from about 5:1 to about 1:5.
Abstract:
Verfahren zum Mischen und Formen von Kompositen aus einer Reaktivharzmatrix, die beim Aushärten duromere Eigenschaften annimmt, und einem Füllstoff, gekennzeichnet durch die folgenden Schritte: (a) Dosieren eines flüssigen oder pastösen Reaktivharzes in einen Extruder, (b) Zugabe von Füllstoff zu dem im Extruder befindlichen Reaktivharz, (c) Vermischen der Komponenten mit Hilfe von einer oder mehreren Extruderschnecken unter Ausbildung eines Komposits, (d) Fördern des Komposits in einen Bereich des Extruders, in der es aufgestaut wird, (e) Entgasen des aufgestauten Komposits, und (f) Fördern des entgasten Komposits durch eine geeignet geformte Düse aus dem Extruder heraus.
Abstract:
A composition and a method are provided for graphene reinforced polyethylene terephthalate (PET). Graphene nanoplatelets (GNPs) comprising multi-layer graphene are used to reinforce PET, thereby improving the properties of PET for various new applications. Master- batches comprising polyethylene terephthalate with dispersed graphene nanoplatelets are obtained by way of compounding. The master-batches are used to form PET-GNP nanocomposites at weight fractions ranging between 0.5% and 15%. In some embodiments, PET and GNPs are melt compounded by way of twin-screw extrusion. In some embodiments, ultrasound is coupled with a twin-screw extruder so as to assist with melt compounding. In some embodiments, the PET- GNP nanocomposites are prepared by way of high-speed injection molding. The PET-GNP nanocomposites are compared by way of their mechanical, thermal, and rheological properties so as to contrast different compounding processes.